Lock

ABSTRACT

The deadbolt of a lock mechanism is operable from either side of the door by means of a pair of independently operable cams controlled, respectively, on the inside by a knob and on the outside of the door by a key-cylinder arrangement. The lock may also be operable and controlled from the inside by a key-cylinder arrangement. Each of the cams is arranged to release a detent mechanism which normally restrains the deadbolt from movement from either of its effective length of the key-cylinder which is unique and adjustable to accomodate a range of door thicknesses. The lock also includes an arrangement by which the outside cover plate cannot be tampered with to gain forceful entry.

United States atent [1 Stoia 1 June 11, 1974 LOCK FOREIGN PATENTS ORAPPLICATIONS 352,419

4/1922 Germany 292/140 r- 1 1- l //a //0 Primary ExaminerAlbert G.Craig, Jr. Attorney, Agent, or Firm-Wolf, Greenfield & Sacks [57]ABSTRACT The deadbolt of a lock mechanism is operable from either sideof the door by means of a pair of independently operable camscontrolled, respectively, on the inside by a knob and on the outside ofthe door by a key-cylinder arrangement. The lock may also be operableand controlled from the inside by a key-cylinder arrangement. Each ofthe cams is arranged to release a detent mechanism which normallyrestrains the deadbolt from movement from either of its effective lengthof the key-cylinder which is unique and adjustable to accomodate a rangeof door thicknesses. The lock also includes an arrangement by which theoutside cover plate cannot be tampered with to gain forceful entry.

14 Claims, 10 Drawing Figures m nnow n 1914 38151390 SHEH 10$ 2 r LOCKSUMMARY OF THE INVENTION As shown in FIGS. 1 and 2 the lock is intendedto be My lock includes a deadbolt which normally is re- 5 mounted on theinterior side of a door l and it in strained between its unlocked orlocked positions by a channel which slidably receives the bolt and whichcooperates with a detent secured to the bolt. The detent and channel arearranged so that the detent will abut either of the opposite ends of thechannel when the deadbolt is in either of its locked or unlockedposition. The channel is movable transversely of the deadbolt to enablethe detent of the deadbolt to be aligned with a slot formed in thechannel parallel to the deadbolt. When the channel has been moved to atransverse position aligning its slot with the detent, the deadbolt thenmay slide to its other position with the detent passing freely throughthe slot in the channel. The channel movement is controlled by either ofa pair of independently operable cams, one cam being operable frominside the door and the other being operable from the outside with anappropriate key. Each of the cams also includes means for urging thebolt to either of its positions. The lock also includes a key-cylinderarrangement which cooperates with 'one of the cams in the manner toenable the lock to be fitted to any of a number of doors of variousthicknesses. The tamper-proof characteristics of the lock are enhancedfurther by a special outside cover plate which reduces the likelihood ofth lock being effectively tampered with from the outside. 4

It is among the object of my invention to provide an improved heavy dutytamper-proof lock mechanism.

Another object of the invention is to provide an improved lock mechanismwhich is of relatively simple construction.

A further object of the invention is to provide a lock mechanism whichissubstantially jam-proof.

Still another object of the invention is to provide a lock mechanismwhich reduces the possibility of malfunction.

A further object of the invention is to provide a lock which isadjustable to fit a range of doors of varying thicknesses withoutrequiring special modification either to the door or the lock.

DESCRIPTION OF THE DRAWINGS The foregoing and other objects andadvantages of the invention will be understood more clearly from thefollowing detailed description thereof, with reference to theaccompanying drawings wherein:

FIG. 1 is an illustration of the lock and keeper as mounted on a doorwith the deadbolt in a locked configuration;

FIG. 2 is an illustration of the lock shown in FIG. 1 as seen along thelines 2 2 of FIG. 1;

FIG. 3 is an elevation of the look as seen from the front side thereofwithout the door and with part of the outside cover plate being brokenaway;

FIG. 4 is a section taken through the lock as seen along the line 4 4 ofFIG. 3;

FIGS. 5 8 show the interior of the lock in various stages as the lock isoperated to shift the deadbolt;

FIG. 9 is a view of the interior of the lock housing cover; and

FIG. 10 is an illustration of that of the cams which is operable fromthe outside of the door.

cludes a hollow casing 12 having appropriate holes formed therethroughto receive fastening screws 14. A deadbolt 16 is slidable along ltslongitudinal axis so that it may be engaged or disengaged with a keeper18 secured to the door jam 20. Appropriate openings are formed in thesidewalls of the casing 12 to enable the opposite ends of the deadbolt16 to pass therethrough.

The deadbolt may be operated either from the inside by either a knob orkey, or from the outside by the key. In some instances it may bedesirable to employ a key operated device on the inside as well as theoutside of the door. The knob 22 and cylinder arrangement 26 areconstructed so that they may be-employed to throw the deadbolt in eitherdirection independently of each other. This is accomplished by employingeither a pair of cams 28, 30 disposed within the casing 12 and which areoperated respectively by'the knob 22 and cylinder arrangement 26. Asdescribed below, rotation of either of the cams is effective to releasethe detent which restrains the bolts and thereafter cause the bolt to bemoved in the desired direction.

The deadbolt 16 is restrained in either of its locked or unlockedpositions by means of a detent pin'or screw 32 which is secured to thebolt. The detent pin 32 is located along the length of the bolt 16 sothat when the bolt is in either the lockedor the unlocked position thedetent will be disposed adjacent either ofthe ends of a channel shapedmember 34 (see FIGS. 5 and 8). Abutment of the detent pin 32 with eitherend of the channel precludes movement of the deadbolt 16 in the intendeddirection. The interior of the casing 12 also includes a cutout portionwhich defines a pocket 36 within each side of the casing to receive thepin 32 when the bolt is in either the locked or unlocked position.

The channel 34 which includes inside and outside walls, 38 40 normallyrests on top of the deadbolt 16 with the deadbolt being received withinthe channel between the walls 38, 40. Means, such as the compressionspring 42 are provided to bias the channel 34-towards the bolt 16 in theconfigurationshown in FIGS. 4 and 5. When the lock parts are in thisposition, the deadbolt 16 is unable to move and it is securely locked.

In order to release the deadbolt 16 for movement to the oppositeposition, aslot 44 is formed at the interior surface of one of the walls40 of the channel-34 and on th same side of the lock as the detent pin32. The bolt 16 is released by moving the channel 34 transversely andaway from the bolt 16 (upwardly as seen in FIG. 4) to bring the detentpin 32 into alignment with the slot 44. Once the pin 32 and slot 44 havebeen aligned the bolt 16 is then free to be moved. The transversemovement of the channel 34 is effected by either of the knob cam 28 orkey cam 30. Each of these cams is of circular configuration except for aflat chordal segment 46, 48, formed onthem, respectively. The chordalsegments 46, 48 of the cams 28, 30 are intended to bear against thelower ends of the walls 38, 40 of the channel 34 when the lock is ineither the locked or unlocked configuration (FIGS. 4 and 5).

g The earns 28, 30 are supported with the casing 12 for rotation along acommon axis which extends centrally through the earns, the knob 22 andthe cylinder assembly 26. As illustrated in FIGSJS and 6, when one ofthe cams is rotated from its normal position its chordal segment engagesthe end of its associated channel wall and urges the channeltransversely of and away from the deadbolt l6 (upwardly as seen in thedrawings). The diameter of the cams and the other dimensions of theparts of the lock are such that when the end of one of the channel wallsis engaged by the circular part of the cam the channel will have beenmoved to the position shown in FIGS. 6 and 7 inwhich the slot 44 in thechannel is in alignment with the detent pin 32 on the deadbolt 16. Asdescribed below, further rotation of the cam'is effective to thereafterurge the bolt to the other position. The slot 44 is maintained inalignment with the detent pin 32 during movement of the bolt by thecircular shape of the cam which maintains the channel in the properposition during rotation of the cam and movement of the bolt.

In order to shift the deadbolt from one position to another, the boltincludes a pair of transverse slots 50, 51 disposed in spaced relationat the midportion of the deadbolt 16. The slots 50 receive and cooperatewith drive pins 52, 53 which are mounted to the inner surfaces of thecams and are spaced radially from the central axis of the cams. Theslots 50, 51 and drive pins 52, 53 are arranged so that as either of thecams is rotated its drive pins will successively enter into andengagethe posite sides of the aligned pin and slot. The lowe end of each ofthe slots may be flared to facilitate entry of the pins.

Thus, as shown in FIG. 6 as one of the cams is rotated the channel 34 israised and simultaneously the pin 52 is rotated upwardly into the slot50 of the deadbolt 16. When the channel has been raised to a height inwhich its slot 44 is aligned with the detent pin 32 continued rotationof the cam maintains the channel at that position while the drive pin 52urges the bolt-l6 to the right as shown in FIG. 6. As shown in FIG. 7 asthe rotation of the cam is continued, the pin 52 withdraws downwardlyfrom the slot 50 while the other pin 53 moves upwardly into engagementwith the slot 51 to continue advancement of the bolt to the right. FIG.8 shows the parts just before the cam has completed one completerevolution with the bolt in its fully shifted position in which thedrive pin 53 has withdrawn from the slot 51 I and with the channel 34moving downwardly to its original position as permitted by engagement ofthe chordal surface of the cam with the lower end of the channel wall.Returnof the channel 34 is assisted by the com-- locks into position,with the bolt in either locked or unlocked position. After the channelhas been returned to its original position with its slot 44. out ofalignment with the dedetent pin 32 the bolt is then restrained in itsshifted position. The bolt may be returned by rotating either of thecams in the opposite direction with the operation of the parts merelybeing reversed.

In the illustrative embodiment of the invention, the cams 28, 30 andchannel 34 are guided in their respective movements by the shape of thehollow interior of the casing 12. In this embodiment the inside of theeasing is of oblong configuration with parallel sidewalls 54 to guidethe channel 34. The lower end of the hollow area is circular to receiveand guide the circular cams 28, 30. The other, upper end of the hollowinterior is shown as also being of circular shape although other shapescould be employed. l-Iere, however. it should be noted that the upwardmovement of channel 34 is limited by the circuiar shape of the upperportion of the hollow interior. Other arrangements may be employed tolimit the extent of upward travel of the channel.

My invention also includes an arrangement by which the locks may beattached to a variety of doors of different thicknesses. This isachieved by the key-cylinder arrangement 26 which can be threaded intothe lock to the extent desired so as to vary the distance between thelock casing 12 and the front cover plate 56 which bears against theoutside surface of the door. In this regard, the interior of the casingI2 is enclosed by a casing cover .58 which is secured to the casing 12by screws 60 threaded into holes 62 formed in the casing 12. The casingcover 58 has a threaded opening 64 in alignment with the axis of thecams. The opening 64 receives the threaded end of a barrel 66, the otherend of the barrel 66 threadably receiving the front cover plate 56.Means are provided for locking the barrel 66 in place after it has beenthreaded into the casing cover 58 to the desired extent. This includes alongitudinal slot 68 formed along the exterior of the barrel 66 whichreceives a movable key 70. The key is biased downwardly (see FIGS. 3 and4) by a spring arrangement 72 and is guided for movement toward and awayfrom the barrel by a slot 74 formed in the casing cover.58. In order toremove or adjust the axial position of the cylinder arrangement 26 thekey must first be raised out of the slot 68 to enable the barrel 66 tobe rotated. Raising of .the keys 70 is facilitated by'a serrated surface76 on the key .70.

In order to enable the key cam 38 to be operated by the key 24, thecylinder arrangement 26 includes a tumbler mechanism 78 rotatablymounted within the barrel 66. The tumbler mechanism 78 is of the typewhich is freely rotatable within the barrel 66 and the key24 only afterthe key has been inserted into the tumbler mechanism 78. In order totransmit rotation of the tumbler mechanism to the key cam 30 a hollowextension 80 is secured to the inner end of the tumbler mechanism 78 forrotation therewith within the barrel 66. The extension 80 is connectedto the key cam 30 by a square or other irregularly shaped plunger 82having one end slidable within the hollow extension 80 and the otherextending out of a square opening in the other end of the extension. Theoutwardly projecting end of the plunger 82 is received within acomplementary depression 84 formed in the surface of the key cam 30. Itis biased into the depression 84 by a spring 86 disposed within theextension 80. The spring-plunger arrangement insures that the end of theplunger 82 will be in firm engagement with the key cam 30 in all theadjusted positions of the cylinder arrangement 26.

In order to enable the cylinder arrangement 26 to be securely threadedinto the casing cover 58 the interior of the cover is provided with aboss 88 having a threaded interior to receive the end of the assembly26. Because of the boss 88 the arrangement for mounting the key cam 30is somewhat different than that for the knob cam'28. The key cam 30includes a circular ridge 90 which 'isrotatably received within ashoulder 92 formed at the inner surface of the boss 88. Cooperation ofthe circular ridge 90, shoulder 92, and the engagement of the circularperiphery with the circular hollow of the casing and engagement of theinwardly facing surface of the key cam 30 with the side of the bolt 16effective to retain the cam 30 in its proper position. The knob cam 28is retained in its proper position and alignment.

A further aspect of the invention relates to the manner in which thefront cover plate 56 is attached to the lock assembly to enhance thetamper-proof characteristics of the lock. The front cover plate 56 has acentral threaded hole 96 which is adapted to be screwed onto the end ofthe assembly 26 which projects through the front of the door. Embeddedwithin the cover plate 56 is a radially extending pin 98 which isslidable within a radially extending-cavity 100 in the plate 56. The pin98 is biased radially inwardly by a spring 102 and'is retained withinthe cavity by a flange 104 at its outer end. After the lock mechanismhas been attached to the door and front cover plate 56 is screwed ontothe front end of the assembly 26 by first depressing pin 98 to enablethe threads on plate 56 to engage the threaded end of the assembly 26.The front cover plate 56 then can be rotated until the pin 98 becomesaligned with a longitudinal slot 104 formed along the surface-of thebarrel 66. The pin 98 then snaps into the slot 106 which precludesfurther rotation of the cover plate 56. The parts are dimensioned sothat when the pin 98 snaps into its locking position the front face ofthe cover plate 56 will be flush with the front end of the cylinderassembly 26. The front cover plate 56 as well as the exposed parts ofthe cylinder assembly 26 are made from a hardened steel toresistdrilling through parts of the lock.

When the lock is attached to the door it can only be removed by firstremoving the front cover plate 56. This in turn can be done only frominside the door and by using a slender probe 108 to disengage the pin 98of the slot 106 and enable the front cover plate 56 to be backed off. Inorder to provide access for the probe from the inside of the door, thecasing 12, cams 28, 30 and casing cover 58 are each provided with holes110, 112, 114, 116 respectively which are arranged in alignment when thelock parts are either in a locked or unlocked position. In order toremove the lock from the door the inside knob 22 is first removed bybacking off the set screw 118 to expose the aligned holes 110, 112, 114,116. The probe 108 then can. be inserted through these holes and intoand along the slot 106 to slide the end of the probe through a hole 102formed in the backside of the front cover plate 56 and into engagementwith the inwardly extending end of the pin 98. The end of the probe 106is wedge-shaped to cooperate with the convex inner end of the pin 98 tourge the pin radially outwardly from the slot 106. The front cover plate56 then can be backed off. The screws 14 then can be removed and thelock mechanism can be withdrawn inwardly from the door. The tamper-proofplate also prevents unauthorized removal of the lock case from the backof the door preventing entry to the outside, other than with the key.(This applies only to double-key-cylinder arrangement wherein anotherkeycylinder is utilized on the inside or back of the lock case insteadof the knob.)

In addition to the security afforded by the heavy duty construction andtamper-proof characteristics of the lock, further feature of the lock isthat it may be installed in any attitude such as with the bolt beingmovable vertically or in an attitude inverted from that shown in thedrawings. This enhances the versatility of the lock and makes itadaptable for use with practically any type of door arrangement. Thelock may be installed without opening the casing which eliminatespossibility of improper installation The lock construction also includesa fail-safe feature in that regardless of the attitude in which thelockis installed it can always be opened from the inside by turning theknob irrespective of the attitude which the lock was installed.

It should be understood that the foregoing description of the inventionis merely to be illustrative thereof and that other embodiments andmodifications may be apparent to those skilled in the art withoutdeparting from the spirit.

Having thus described the invention what I desire to claim and secure byLetters Patent is:

l. A lock mechanism comprising:

a casing;

a deadbolt slidable along an axis within said casing, said deadbolthaving an end thereof extending throughian opening formed in saidcasing;

a detent member within said casing and being mounted therein formovement transversely of the axis of said deadbolt;

said detent member having a surface thereof facing a surface of saiddeadbolt, said surface ofsaid detent member having a slot formed thereinwhich extends along a direction parallel to said axisv of said deadbolt;

means forming a projection on said deadbolt extending from said facethereof, said projection being alignable with said slot in said detentmember when said detent member is moved to a predetermined position inrelation to said deadbolt;

a first cam mounted with said housing, said first car'n being operablefrom one side of said casing for moving said detent member to saidpredetermined position to enable said deadbolt to move along said axis,said first cam further including means for thereafter moving saiddeadbolt along said axis;

a second cam disposed within said housing and being operable from theother side of said housing for moving said detent member to saidpredetermined position to enable said deadbolt to move along said axis,said second cam means including means for thereafter moving saiddeadbolt along said axis;

and

said first and second cams being dently of each other.

2. A lock as defined in claim 1 further comprising;

said member being in the'form of a channel having a pair of spacedwalls, said deadbolt extending through said channel between said wallswith said walls straddling said bolt;

each of said channel walls being operably engageable by one of saidcams.

3. A lock as defined in claim 1 wherein said means on said first andsecond cams for moving said deadbolt comprises:

means forming at least one slot in said bolt;

at least one pin mounted to each of said cams, said pins being disposedin relation to said slot in said bolt so that when each of said cams isoperated,

operable indepensaid pin wili engage said slot after said detent memberhas been moved, said cam pin and slot being arranged so that continuedmovement of said cam will urge said deadbolt along said axis thereof.

4. A lock as defined in claim 1 further comprising:

means biasing said member transversely towards said dead-bolt.

'. A lock as defined in claim 2 further comprising:

each of said cams being circular in shape and being mounted for rotationwithin said casing on the opposite side of the dead-bolt and that onwhich said channel is disposed, each of said cams being mounted inalignment with the free ends of one of said channel walls, each of saidcams having a flat chordal portion adapted to engage its associated endof its associated channel wall.

6. A lock as defined in claim 5 wherein said cams are mounted forrotation along a common axis.

7. A lock as defined in claim 5 wherein said means mounting said camsfor rotation comprises: the hollow interior portion of said lock casingdefining. circular surfaces on that side of said bolt in which said camsare mounted, said circular surfaces receiving said cams.

8. A lock as defined in claim 2 further comprising:

the interior of said casing defining a hollow portion which extendstransversely of said deadbolt, said hollow portion defining wallsurfaces in sliding engagement with the ends of said member to guidesaid member in said movement thereof.

9. A lock mechanism comprising:

a casing;

a deadbolt slidable along an axis within said casing, said deadbolthaving an end thereof extending through an opening formed in saidcasing;

detent means within said casing engageable with said dead-bolt forprecluding movement of said deadbolt along saidaxis;

a first cam mounted within said housing, said first cam being operablefrom one side of said casing for moving said detent means to a positionin-which said deadbolt is free to move along said axis, said first camfurther including means for thereafter moving said deadbolt along saidaxis;

a second cam disposed within said housing and being operable from theother side of said housing for moving said detent means to a position inwhich said deadbolt is free for movement along said axis,

said second cam means including means for thereafter moving saiddeadbolt along said axis;

said first and second cams being operable independently of each other;

a barrel having a key-circular disposed therein at one end thereof, saidkey-circular being rotatable within said barrel in response to insertionof a key into said key-cylinder;

means threadably mounting the other end of said barrel to said casingalong an axis which is coaxial with at least one of said cams;

means connecting said key-cylinder to said one of said cams;

said threadable mounting means for said barrel being constructed toenable saidbarrel to project from said easing into a variable extent toenable the effective barrel length to be adjusted to accomodate doors ofvarying thickness; and

means for locking said barrel to said casing.

10. A lock as defined in claim 9 wherein said means connecting saidkey-cylinder to said one cam comprises;

a plunger connected to the other end of said keycylinder for rotation inunison therewith; means biasing said plunger awayfrom said cylinder andtoward said one cam; and said one cam including socket means receptiveto said plunger for engagement therewith to enable said one cam to berotated in unison with said keycylinder. 11. A lock as defined-in claim9 wherein said means for locking said barrel to said casing'comprises:

means forming a longitudinal keyway exteriorly of said barrel andintersecting the threaded end thereof adapted to be screwed into saidcasing; and

a key mounted to said casing for movement toward and away from thethreaded end of said barrel and means biasing said key toward saidbarrel to normally engage said keyway.

12. A lock as defined in claim ll further comprising:

said key being exposed through said casing at the same side thereof fromwhich said barrel extends, said side being adapted to bear against theinside surface of a door whereby said key is hidden when said lock ismounted on said door.

13. in a lock mechanism including a casing a bolt slidable along an axisextending through a casing and means inside said casing operable toslide said bolt along its axis, an improved arrangement for securingsaid lock to a door or the like comprising, in combination:

a barrel having a key-cylinder disposed therein at one end thereof, saidkey-cylinder rotatable within said barrel in response to insertion of akey into said cylinder;

means threadably mounting the other end of said bar rel to said casing;

means connecting said key-cylinder to said bolt operating means;

said threadable mounting means for said barrel being constructed toenable said barrel to extend from said casing to a variable extent toenable the effective barrel length to be adjusted to accomodate doors ofvarying thickness;

means for locking said barrel to said casing in said adjusted positionincluding means forming a longitudinal key-way exteriorly of saidbarreland intersecting the threaded end thereof adapted to be screwed intosaid casing and a key mounted to said casing for movement toward andaway from the threaded end of said barrel and means biasing saidkey'toward said barrel to normally engage said keyway.

14. In a lock adapted to be mounted on a door including a lock mechanismsecured to the interior of said door and a key-cylinder arrangementmounted to said lock mechanism and extending through an opening in saiddoor with the end of said cylinder arrangement being exposed at thefront of said door, an improved cover plate comprising:

said cover plate having threaded hole formed therethrough adapted to bescrewed on to the outwardly exposed end of said cylinder arrangement;

a pin mounted within said front cover plate and extending radiallythereof, said pin being movable between a locking position in which theinner end thereof extends radially into said hole and an unlockedposition which said pin is retracted into said cover plate;

means biasing said pin radially inwardly;

means forming a slot on the exterior threaded end of said cylinderarrangement, said slot being constructed and arranged as to receive saidpin when cept through said passage.

1. A lock mechanism comprising: a casing; a deadbolt slidable along anaxis within said casing, said deadbolt having an end thereof extendingthrough an opening formed in said casing; a detent member within saidcasing and being mounted therein for movement transversely of the axisof said deadbolt; said detent member having a surface thereof facing asurface of said deadbolt, said surface of said detent member having aslot formed therein which extends along a direction parallel to saidaxis of said deadbolt; means forming a Projection on said deadboltextending from said face thereof, said projection being alignable withsaid slot in said detent member when said detent member is moved to apredetermined position in relation to said deadbolt; a first cam mountedwith said housing, said first cam being operable from one side of saidcasing for moving said detent member to said predetermined position toenable said deadbolt to move along said axis, said first cam furtherincluding means for thereafter moving said deadbolt along said axis; asecond cam disposed within said housing and being operable from theother side of said housing for moving said detent member to saidpredetermined position to enable said deadbolt to move along said axis,said second cam means including means for thereafter moving saiddeadbolt along said axis; and said first and second cams being operableindependently of each other.
 2. A lock as defined in claim 1 furthercomprising; said member being in the form of a channel having a pair ofspaced walls, said deadbolt extending through said channel between saidwalls with said walls straddling said bolt; each of said channel wallsbeing operably engageable by one of said cams.
 3. A lock as defined inclaim 1 wherein said means on said first and second cams for moving saiddeadbolt comprises: means forming at least one slot in said bolt; atleast one pin mounted to each of said cams, said pins being disposed inrelation to said slot in said bolt so that when each of said cams isoperated, said pin will engage said slot after said detent member hasbeen moved, said cam pin and slot being arranged so that continuedmovement of said cam will urge said deadbolt along said axis thereof. 4.A lock as defined in claim 1 further comprising: means biasing saidmember transversely towards said dead-bolt.
 5. A lock as defined inclaim 2 further comprising: each of said cams being circular in shapeand being mounted for rotation within said casing on the opposite sideof the dead-bolt and that on which said channel is disposed, each ofsaid cams being mounted in alignment with the free ends of one of saidchannel walls, each of said cams having a flat chordal portion adaptedto engage its associated end of its associated channel wall.
 6. A lockas defined in claim 5 wherein said cams are mounted for rotation along acommon axis.
 7. A lock as defined in claim 5 wherein said means mountingsaid cams for rotation comprises: the hollow interior portion of saidlock casing defining circular surfaces on that side of said bolt inwhich said cams are mounted, said circular surfaces receiving said cams.8. A lock as defined in claim 2 further comprising: the interior of saidcasing defining a hollow portion which extends transversely of saiddeadbolt, said hollow portion defining wall surfaces in slidingengagement with the ends of said member to guide said member in saidmovement thereof.
 9. A lock mechanism comprising: a casing; a deadboltslidable along an axis within said casing, said deadbolt having an endthereof extending through an opening formed in said casing; detent meanswithin said casing engageable with said dead-bolt for precludingmovement of said deadbolt along said axis; a first cam mounted withinsaid housing, said first cam being operable from one side of said casingfor moving said detent means to a position in which said deadbolt isfree to move along said axis, said first cam further including means forthereafter moving said deadbolt along said axis; a second cam disposedwithin said housing and being operable from the other side of saidhousing for moving said detent means to a position in which saiddeadbolt is free for movement along said axis, said second cam meansincluding means for thereafter moving said deadbolt along said axis;said first and second cams being operable independently of each other; abarrel having a key-circular disposed Therein at one end thereof, saidkey-circular being rotatable within said barrel in response to insertionof a key into said key-cylinder; means threadably mounting the other endof said barrel to said casing along an axis which is coaxial with atleast one of said cams; means connecting said key-cylinder to said oneof said cams; said threadable mounting means for said barrel beingconstructed to enable said barrel to project from said casing into avariable extent to enable the effective barrel length to be adjusted toaccomodate doors of varying thickness; and means for locking said barrelto said casing.
 10. A lock as defined in claim 9 wherein said meansconnecting said key-cylinder to said one cam comprises: a plungerconnected to the other end of said key-cylinder for rotation in unisontherewith; means biasing said plunger away from said cylinder and towardsaid one cam; and said one cam including socket means receptive to saidplunger for engagement therewith to enable said one cam to be rotated inunison with said key-cylinder.
 11. A lock as defined in claim 9 whereinsaid means for locking said barrel to said casing comprises: meansforming a longitudinal keyway exteriorly of said barrel and intersectingthe threaded end thereof adapted to be screwed into said casing; and akey mounted to said casing for movement toward and away from thethreaded end of said barrel and means biasing said key toward saidbarrel to normally engage said keyway.
 12. A lock as defined in claim 11further comprising: said key being exposed through said casing at thesame side thereof from which said barrel extends, said side beingadapted to bear against the inside surface of a door whereby said key ishidden when said lock is mounted on said door.
 13. in a lock mechanismincluding a casing, a bolt slidable along an axis extending through acasing and means inside said casing operable to slide said bolt alongits axis, an improved arrangement for securing said lock to a door orthe like comprising, in combination: a barrel having a key-cylinderdisposed therein at one end thereof, said key-cylinder rotatable withinsaid barrel in response to insertion of a key into said cylinder; meansthreadably mounting the other end of said barrel to said casing; meansconnecting said key-cylinder to said bolt operating means; saidthreadable mounting means for said barrel being constructed to enablesaid barrel to extend from said casing to a variable extent to enablethe effective barrel length to be adjusted to accomodate doors ofvarying thickness; means for locking said barrel to said casing in saidadjusted position including means forming a longitudinal key-wayexteriorly of said barrel and intersecting the threaded end thereofadapted to be screwed into said casing and a key mounted to said casingfor movement toward and away from the threaded end of said barrel andmeans biasing said key toward said barrel to normally engage saidkey-way.
 14. In a lock adapted to be mounted on a door including a lockmechanism secured to the interior of said door and a key-cylinderarrangement mounted to said lock mechanism and extending through anopening in said door with the end of said cylinder arrangement beingexposed at the front of said door, an improved cover plate comprising:said cover plate having threaded hole formed therethrough adapted to bescrewed on to the outwardly exposed end of said cylinder arrangement; apin mounted within said front cover plate and extending radiallythereof, said pin being movable between a locking position in which theinner end thereof extends radially into said hole and an unlockedposition which said pin is retracted into said cover plate; meansbiasing said pin radially inwardly; means forming a slot on the exteriorthreaded end of said cylinder arrangement, said slot being constructedand arranged as to receive said pin when said cover plate is thrEadedonto the end of said cylinder arrangement; and means forming a passageway through said lock mechanism and said door to enable an instrument tobe inserted therethrough into said slot in said barrel whereby said pinmay be urged to its retracted position within said cover to enableremoval of said plate, said pin being inaccessible except through saidpassage.